Practical application of synthetic head models in real ballistic cases

Abstract

In shooting crimes, ballistics tests are often recommended in order to reproduce the wound characteristics of the involved persons. For this purpose, several “simulants” can be used. However, despite the efforts in the research of “surrogates” in the field of forensic ballistic, the development of synthetic models needs still to be improved through a validation process based on specific real caseworks. This study has been triggered by the findings observed during the autopsy performed on two victims killed in the same shooting incident, with similar wounding characteristics; namely two retained head shots with ricochet against the interior wall of the skull; both projectiles have been recovered during the autopsies after migration in the brain parenchyma. The thickness of the different tissues and structures along the bullets trajectories as well as the incident angles between the bullets paths and the skull walls have been measured and reproduced during the assemblage of the synthetic head models. Two different types of models (“open shape” and “spherical”) have been assembled using leather, polyurethane and gelatine to simulate respectively skin, bone and soft tissues. Six shots have been performed in total. The results of the models have been compared to the findings of post-mortem computed tomography (PMCT) and the autopsy findings.Out of the six shots, two perforated the models and four were retained. When the projectile was retained, the use of both models allowed reproducing the wounds characteristics observed on both victims in terms of penetration and ricochet behaviour. However, the projectiles recovered from the models showed less deformation than the bullets collected during the autopsies. The “open shape” model allowed a better controlling on the shooting parameters than the “spherical” model. Finally, the difference in bullet deformation could be caused by the choice of the bone simulant, which might under-represent either the strength or the density of the human bone. In our opinion, it would be worth to develop a new, more representative material for ballistic which simulates the human bone.

Interpol review of forensic firearm examination 2019–2022

“…Overall bullet penetration was similar to the documented wounds of the deceased, but bullet deformation of the bullets that were fired at the model was slightly less. In the other study, two young males died as a result of a single headshot wound each, inflicted with full metal jacket bullets from the same .25 Auto caliber pistol [ 137 ]. The shots were reproduced with a ‘closed’ (spherical) and an ‘open’ model.…”

Modern Global Scientific Trends of Forensic Research Methods in Cases of Firearm Trauma

“…Вчені з Університетського центру судової медицини (м. Лозанна, Швейцарія) запропонували проводити реконструкцію фатальної вогнепальної травми голови за допомогою відкритої та закритої моделей [24]. Відкрита модель голови передбачала симулятор шкіри, 10 % желатин як підшкірно-жирову клітковину, поліуретанову пластинку як імітатор кісток черепа та 10 % желатин як симулятор головного мозку.…”